Austenitic alloy and weld

ABSTRACT

Sound, ductile austenitic alloy and weld of high strength in the as-welded condition. The alloy essentially consists of an ironchromium-nickel-manganese austenitic matrix with a second phase comprising a columbium compound, the columbium-rich phase serving to host non-metallic impurities such as phosphides, sulphides, silicides and borides and preclude their depositing in the austenitic grain boundaries. The alloy contains about 12% to 30% chromium, about 10% to 55% nickel, about 5% to 15% manganese, up to 3% molybdenum, carbon about 0.03% to .20%, nitrogen about 0.03% to 0.30%, with 0.5% to 4.5% columbium and/or 1% to 7% tungsten, and remainder iron, this amounting to at least about 22%.

United States Patent Espy, Ronald H. et al.

[ 51 May2,1972

[54] AUSTENITIC ALLOY AND WELD [72] Inventors: Ronald R, Espy,Randallstown; Elbert E.

[73] Assignee:

[52] U.S.Cl ..75/128 A, 75/1286 [51 Int. Cl 1 ..C22c 39/20 [58] Fieldot'Search ..75/128 A, 128 N, 128, 125

[56] References Cited UNITED STATES PATENTS 2,892,703 6/1959 Furman..75/128 A 3,152,934 10/1964 Lula ....75/l28 N 3,201,233 8/1965 Hull..75/128 N 3,306,736 2/1967 Rundell ..75/128N 3,495,977 2/1970 Denhard..75/128N Primary Examiner-l-lyland Bizot Attorney-John Howard Joynt [57] ABSTRACT Sound, ductile austenitic alloy and weld of high strength inthe as-welded condition. The alloy essentially consists of anironchromium-nickel-manganese austenitic matrix with a second phasecomprising a columbium compound, the columbiumrich phase serving to hostnon-metallic impurities such as phosphides, sulphides, silicides andborides and preclude their depositing in the austenitic grainboundaries. The alloy contains about 12% to 30% chromium, about 10% to55% nickel, about 5% to 15% manganese, up to 3% molybdenum, carbon about0.03% to 20%, nitrogen about 0.03% to 0.30%, with 0.5% to 4.5% columbiumand/or 1% to 7% tungsten, and remainder iron, this amounting to at leastabout 22%.

9 Claims, No Drawings AUSTENITIC ALLOY AND WELD As a matter ofintroduction, our invention in a sense is a companion to that describedand claimed in the copending Application Ser. No. 491,880 ofDenhard-Espy, filed Sept. 30, 1965, and entitled Stainless SteelResistant to Stress Corrosion Cracking, now US Pat. No. 3,495,997,issued Feb. 17,

1970 and relates to the austenitic iron-chromium nickel-man austeniticcorrosion-resistant alloy of high strength and good ductility over awide range of operating temperatures."

Another object is the provision of a fully austenitic stainless steel ofgood workability which is readily weldable and which in the as-weldedcondition is possessed of good tensile strength, ductility andresistance to impact, all over a wide' temperature range, that is, fromabout 320 F. up to about A further object is the provision of a weldmetal and weld which are sound and free of defects and which are strong,ductile and of good impact strength.

Other objects of our invention in part will become readily apparent inthe course of the description which follows and in part will be moreparticularly pointed to.

Accordingly, our invention in general may be considered to reside in thecombination of elements, in the composition of the ingredients, and inthe relation between the same, all as described herein and particularlyset forth in the claims made at the end of this specification.

BACKGROUND OF THE INVENTION In order to gain a better understanding ofcertain features of our invention, it may be noted at this point thatmost 'of the iron-chromium-nickel alloys which are fullyaustenitic, andparticularly the fully austenitic chromium-nickel stainless steels, areinclined to develop cracks as a result of welding. Hot cracks willdevelop when these alloys are heated to a tem perature of some 2,300 F.,especially those alloys in the form" of heavy section. Even in thelighter sections, where'bending or other relief of stress is restrained,cracks also are likely to tial amount. Moreover, in applications where'awholly nonmagnetic structure is necessary, as in electrical instruments,

instrument panels, and the like, not even a small amount of'delta-ferrite can be tolerated because of the ensuing magnetic effects.Perhaps even more importantly, we find that a'ferritecontaining alloydevelops sigma phase at elevated temperatures, with resulting loss inmechanical properties, and even causing hot-working difficulties.

And while the nickel-base alloys and many of the chroniumnickel-basealloys of the prior art are fully austenitic and free of delta-ferrite,we find that these alloys also are inclined to develop cracks as aresult of a welding operation. This we attribute to the appearance oflow melting compounds along the grain boundaries. The appearance ofthese compounds is especially pronounced in welds or weld deposits asthe weld metal solidifies and cools during the course of the weldingoperation. The low melting compounds particularly involved are found tobe phosphides, silicides and borides and, to a' lesser extent, thesulphides. Such compounds formingin the grain boundaries weaken themetal, particularly causing a loss of hot tensile strength, resulting inthe occurrence of hotcrack defects.

For many welding applications there are available a number ofnickel-base alloys, these containing the ingredients chromiumandmanganeserSee, for example, the alloy described in the Witherell U.S.Pat. No. 3,113,021 of Dec. 3, 1963, typically analyzing'about 18.5% to21.5% chromium, about 2.75% to 3.25% manganese, about 2.25% to 2.75%columbium, about 0.2% to about 0.5% titanium, with iron up to about 2%,carbon up to about 0.08%, silicon less than about 0.3%, alu-' minum lessthan 0.08%, and remainder'nickel, this in the amount of about69.5%(Patent, column 3, lines 56 through 63). The alloy is costlybecause of the high nickel content; And because of the'high nickelcontent it is difficult to work in the mill. Moreovenin many instancesthealloy is found to be sensitive to hot-cracking in the weld metal.

An object of my invention, therefore, is the provision of a fullyaustenitic iron-chromium-nickel-manganese alloy possessing a goodcombination of strength, ductility and impact resistance which is suitedto applications over a wide range of temperatures, which alloy readilylends itself to welding 'by known and accepted techniques, includingelectric-arc welding in controlled atmosphere, and which, indeed, isitself suited to applications as a weld-metal, as in thewelding ofhighly alloyed'stainless steels and other alloys, as, for example, theknown 20-45-5 alloy (about 20% chromium, about 45% nickel, about 5%manganese, and remainder iron) and the 21- 6-9 (about 21% chromium,about 6% nickel, about 9% manganese, and remainder iron), which alloyand weld are sound and free of defects, having properties compatiblewith those of the unwelded base metal.

SUMMARY OF THE INVENTION Now'referring moreparticularly to the practiceof our invention, we provide an iron-chromium-nickel-manganese alloywhich essentially contains'particular amounts of the ingredients'carbonand/or nitrogen,-together with columbium and/or tungsten. The furtheringredients sulphur, phosphorus, silicon and'boron, commonly present instainless steel and like alloys, are maintained within practical butcontrolled amountspln the alloyof our invention there is employedchromium'in the amount of about 12% to 30% and preferably about 12%to25%, nickel in the amountof'about' 10% 'or 15% to 55% and preferablyabout 12% to 45% or more especially about 20%'to about45%, manganesein'the amount of about 5% to 15% and'preferably about 9% to 13%, andatleast one of the ingredients columbium in the amount of about 0.5% to4.5%, preferably about 1% to about 4%, or tungsten in the amount ofabout 1% to 7%, preferably about 3% to about 7%,

with iron amounting to about 22% to 72%, usually about 22% to about 66%.In our alloy carbon necessarily is present, this in the amount of about0.03% to 0.20% and preferably 0.03% to 0.15% or 'even' about 0.04% toabout 0.12%. Nitrogen is present in the amount of about 0.03% to 0130%or'about 0.03% to about0.25% or even about 0.06% to about 0.25%. The sumof the ingredients carbon'and nitrogen amounts to at least about 0.15%where the columbium content amounts to only about 0.5% or the tungstencontent only about 1%, and at least about 0.10% where the columbiumcontent is about 1%. The ingredients phosphorus and sulphur are presentin residual amount, the phosphorus being in amounts up:to about 0.020%andthe sulphur in amounts up to about 0.020% or even to about 0.035%.Boron ordinarily is less than 0.001%, although where columbium'and/ortungsten are on the'high side, boron purposely may be added to improvethe hot-workability of the metal, but in an amount not exceeding 0.007%.

The silicon content of the alloy should not exceed 0.75%, and

for best results is maintained at a value less than 0.65%, this usuallyranging from 0.30% to 0.60%. Where desired, molybdenum may be employedin amounts up to about 3%.

Our alloy is austenitic. But we find that columbium and/or tungstenintroduced in large amount go to form columbiumrich or tungsten-richcompounds, as thecase maybe, with the iron, carbon and nitrogen present.The columbium compound or tungsten compound is in the nature of a secondphase which exists along and with the primary austenitic phase. And thissecond phase serves to break up the grain structure and distribute thephosphides, sulphides, borides and silicides which form in the meltingand teeming of the metal, this within the grains rather than at thegrain boundaries. Microscopic examination clearly reveals a distributionof these compounds within the second phase; the grain boundaries of thealloy thus remain substantially uncontaminated.v Strength, ductility andhigh impactresistance thus are assured. Moreover, we find that with theassured freedom from the precipitation of phosphides, sulphides, boridesand silicides in the austenitic grain boundaries, there is littletendency for them to nucleate and foster corrosive attack. While weprefer not to be bound by a theoretical explanation, it is our view thatwhere it is columbium that is employed, the second phase is a columbiumcarbide, or perhaps columbium nitride or even acolumbium-iron-carbon-nitrogen compound. Where tungsten is employed, itis thought that the second phase is a tungsten carbide or a tungstennitride, or even some tungsten-iron-carbon-nitrogen compound.

In our iron-chrornium-nickel-manganese-columbium/tungsten alloy thecomposition is in every sense critical. For we find that where one ormore of the ingredients is eliminated, or, indeed, where any significantdeparture is made from either the assigned minimum values or requiredmaximum values, the desired combination of properties is no longer had.More particularly, chromium is employed in the amount of about 12% toabout 30%, preferably some 13% to about 25%. With a chromium contentless than about 12%, corrosion-resistance suffers. And where thechromium content exceeds about 25%, and certainly where'it exceeds about30%, hotworkability directly suffers. Moreover, with the excessivechromium content the metal is inclined to become ferritic, particularlywhere the nickel content approaches the low side of the permissiblerange.

The nickel content of our alloy is in the amount of about on the lowside to about 55% on the high. With a nickel content less than about 10%the stability of the metal is adversely affected, the alloy inclining tobecome ferritic. And with nickel exceeding about 55%, thehot-workability is adversely affected. And, even more importantly, weare inclined to the view that'the solubility of the metal for carbon andnitrogen, two essential ingredients, is adversely affected, nickelobjectionably decreasing the solubility of the'metal for both. Thenickel content for best results amounts to about 15% to about 40%.

A manganese content of about 5% to about 15% is required, for with amanganese content less than about 5% I feel that there is insufficientsupport for the necessary nitrogen content. And with manganese exceedingabout 15% we feel that ferrite is introduced at elevated temperatures.Moreover, the corrosion-resistance suffers. For best results manganeseis employed in the amount ofabout 9% to about 13%.

lron is a necessary and essential constituent in my alloy, thisamounting to about 22% to about 72%. The iron serves as a vehicle forthe carbon and nitrogen present and, moreover, is thought to be one ofthe ingredients present in the columbium/tungsten second phase. At leastabout 22% iron is required for the purposes noted; iron should notexceed about 72%, however, in view of the necessary requirements forchromium, nickel, manganese and columbium/tungsten. In general, the ironcontent ranges from about 22% to about 55%.

In our alloy, as noted above, at least one of the ingredients columbiumin the amount of 0.5% to 4.5% or tungsten in the amount of about 1% toabout 7% is necessary in order to serve as a basis for the requiredsecond phase. A columbium content less than about 0.5% is insufficientfor that purpose. And a columbium content exceeding about 4.5% adverselyaffects the hot-workability of the metal. And the excessive columbiumcontent moreover is inclined to result in undesired hardening, that is,age-hardening or precipitation-hardening, as .the metal is cooled fromelevated temperatures. While the excessive columbium content increasesthe tensile strength, it adversely affects the ductility andimpact-resistance. In general,

the same may be said with respect to the tungsten content; less 1 thanabout 1% tungsten is insufficient and a tungsten content exceeding about7% creates undesired problems in working the metal, in giving anundesired hardening in cooling from high temperature, and in loss ofcorrosion-resistance.

Although the carbon content of our alloy ranges from about 0.03% to0.20%, for best results there is employed a carbon content of 0.04% to0.12%. A carbon content less than about 0.04%, and certainly one lessthan about 0.03%, affords insufficient carbon for the required secondphase noted. And a carbon content exceeding 0.12%, and particularly oneexceeding about 0.15%, adversely affects corrosion-resistance. Ingeneral, the same may be said with respect to the ingredient nitrogen,at least 0.03%, and preferably 0.06% nitrogen being required in order tocontribute to the second phase noted, but nitrogen exceeding about0.25%, and certainly in excess of 0.30%, adversely affects ductility andimpact-resistance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS While, as noted above, thealloy of our invention broadly ranges in composition from about 12% toabout 30% chromium, about 10% to about 55% nickel, about 5% to about 15%manganese, with carbon about 0.03% to about 0.20%, nitrogen about 0.03%to 0.30%, phosphorus in amounts up to about 0.020%, sulphur in amountsup to about 0.035%, and any boron in an amount not exceeding 0.007%, andwith columbium in the amount of 0.5% to about 4.5% and/or tungsten inthe amount of about 1% to about 7%, withremainder iron, there are anumber of more limited compositions in which a best combination ofproperties is enjoyed. In all, however, the alloy is fully austenitic,strong, tough and ductile. Moreover, the alloy is suited to applicationsthroughout a wide temperature range. The alloy is readily weldable and,in point of fact, peculiarly suited to applications as a weld fillermateria1, giving a sound weld which is possessed of a good combinationof properties in the as-welded condition.

One of the preferred alloys according to our invention es sentiallyconsists of about 12% to about 15% chromium, about 18% to about 24%nickel, about 9% to about 13% manganese, with about 0.06% to about 0.15%carbon, about 0.03% to 0.20% nitrogen, about 1.5%. to about 3.5%columbium, phosphorus not exceeding about 0.020%, and remainder iron.More specifically, this alloy essentially consists of about 13% to about14% chromium, about 18% to about 22% nickel, about 10% to about 11%manganese, about 0.03% to about 0.11% carbon, about 0.06% to about 0.20%nitrogen, with about 1.5% to about 3.5% columbium, and about 49% toabout 57% iron. Both the preferred and the specific alloy are consideredto be stainless steels, fully austenitic, and sufficientlycorrosion-resistant for most applications. They are suited to a varietyof welding applications, particularly as a filler material. And in theas-welded condition are strong, tough and ductile.

A further preferred alloy, this likewise being considered a stainlesssteel, essentially consists of about 15% to about 22% chromium, about10% to about 22% nickel, about 7% to about 13% manganese, about 0.05% toabout 0.12% carbon, about 0.03% to about 0.20% nitrogen, about 1.5% toabout 2.5% columbium, with remainder substantially iron. Because of theincreased chromium content this alloy enjoys excellent corro'sion-resistance, along with good strength, ductility and toughness inthe as-welded condition. Moreover, the alloy is suited to applicationswhere there is encountered a rather wide range of operatingtemperatures.

7 Another preferred alloy essentially consists of about 16% to about 21%chromium, about 35% to about 45% nickel, about 9% to about 13%manganese, phosphorus not exceeding about 0.020%, with carbon about0.06% to about 0.12%, nitrogen about 0.06% to about 0.20%, columbiumabout 1% to about 4%, and remainder substantially iron, this amountingto at least 22%. This alloy enjoys good stress-corrosioncrack-resistance in combination with good weldability. Where desired,molybdenum may be added in amounts up to about 3%.

A still further preferred alloy essentially consists of about 22% toabout 27% chromium, about 18% to about 23% nickel, about 9% to about 13%manganese, with a carbon content of about 0.06% to about 0.10%, anitrogen content of about 0.06% to about 0.20%, a columbium content ofabout 1% to about 2%, and remainder substantially iron. Perhaps theoutstanding virtue of this alloy is its combination ofcorrosion-resistance, strength and toughness over a wide range intemperatures, that is, from about -320 F. to about 1,500 F.

in applications involving a welding of the 20-45-5 grade of stainlesssteel (about 20% chromium, about 45% nickel and about 5% manganese, withremainder substantially iron) we prefer an alloy essentially consistingof about 17% to about 22% (more broadly about 12% to about 25%)chromium, about 30% to about 45% (or more especially about 35% to about40%) nickel, about 5% to about 12% (or especially about to about 12%)manganese, about 0.03% to about 0.20% (or more particularly about 0.06%to about 0.12%) carbon, about 0.03% or 0.04% to about 0.20% nitrogen,about 1% to about 3% or 4% columbium, up to about 3% molybdenum, andremainder substantially iron, this amounting to at least 22%, moreparticularly about 22% to about 42% iron. Boron may be added in amountsup to about 0.007% where desired. This alloy has especially goodcorrosion-resisting characteristics which make it suited to marineapplications. For a best combination of properties this alloyessentially consists of about 19.5% to about 20.5% chromium, about 44.5%to about 45.5% nickel, about 5% to about 6% manganese, about 0.03% toabout 0.05% carbon, about 0.03% to about 0.06% nitrogen, about 1.5% toabout 2% columbium, and remainder substantially iron.

1n the welding of the 21-6-9 grade of stainless steel (about 21%chromium, about 6% nickel, about 9% manganese and remainder iron) ourpreference is for an alloy essentially consisting of about 12% to about27% (more particularly about 24% to about 26%) chromium, about 17% toabout 24% (or more particularly about 20% to about 22%) nickel, about 9%'lensile propertics,-fracture appearance and microstructure of thealloys of these alloys, with high nickel content, give a sound weldwhich is fully austenitic, tough and ductile in the as-welded condition,even where subjected to duty at low temperatures.

As particularly illustrative of the alloy of my invention we givebelowin Table 1(a) the chemical compositions of some nine alloys, fouraccording to our invention and five of composition outside of ourinvention, in which'there are forcefully revealed the effects ofmanganese, columbium and carbon on the production of crack-free welds.The compositions in every case are those of the deposited weldmetal.'The tensile properties and a notation respecting the appearanceof the fractured tensile specimens, as well as the amount of a secondphase present in the alloy, are given in Table 1(b).

TABLE I B Chemical composition of nine austenitic stainless steel welddeposits Specimen N o. 0 Mn P S Si Cr Ni C b N 9. 35 .009 .005 .40 20.2011.90 .31 1. 9.1 .012 .011 .40 13.46 20.69 .05 9. 71 .008 .011 .45 13.79 19.19 .04 9. 03 .007 013 19 13. 28 19. 83 14 11.88 .001 .010 6413.110 19. 3. 17 .22 1. 31 005 014 52' 13. 84 20. 27 1.9 1 .01 11.111012 007 38 13.11 .21. .25 .2. (I8 .03 ll. 31 013 U119 .37 2-1. 65 .21..2-1 1.50 05 11.88 .67 1.10

Alleys of the invention. Alloys of the invention enjoying.' it bestcenihinntion of properties.

The tensile properties of the weld compositions of table 1(a) in theform of weld specimens of 0.505 inch diameter are reported below inTable 1(b). There are given the ultimate tensile strength in kilopoundsper square inch (ksi), the yield strength in ksi, the percent elongationin 2 inches, and the percent reduction in'area. Also reported is theappearance of the fractured tensile specimens, with percent indicationof the number of microfissures or hot-cracks which occurred at the timeof welding each specimen and which later show up as defects on the faceof the fractured specimen. Additionally, there is indicated the volumepercent of a second'phase which is observed in the microstructure ofeach specimen, these by visual estimate at 300x.

TABLE 10) Till): lei

Appearance of fractured tensile specimens Average Percent MF 1 on Breaks2 on phase in Specimen U.'1.S Y.S., elong. Percent fractured side ofmicro- No. K s 1 K s.i. 2 R. face specimen structure 73 57 18 16 3Several 5 83 63 31 39 0 None 5 MF=Micr0fissures or hot-cracks whichoccurred at the time of welding show up as defects on the face of thefractured specimen.

2 Breaks on side of specimen are a good measure of weld depositsoundness.

Ihis was mostly micro condition, a condition where fracture occurs alongthe grain boundary in tensile loading.

Alloys of the invention.

b Alloys of the invention enjoying a best combination of properties.

or 10% to about 12% manganese, with a carbon content of about 0.03% toabout 0.12% (or about 0.06% to about 0.l0% carbon), a nitrogen contentof about 0.03% toabout 0.30% (more especially about 0.06% to about 0.20%nitrogen), with about 1.5% to about 3% (or even about 1% to about 2%)columbium, and remainder substantially iron, although molybdenum may bepresent in amounts up to about 2%. And, here again, for a bestcombination of properties, however, we employ an alloy essentiallyconsisting of about 21% chromium, about 20% nickel, about 9% manganese,with a carbon content of about 0.03% to about 0.06%, a nitrogen contentof about 0.03% to about 0.10%, with about 1.5% to about 2% columbium,and remainder substantially iron. We find that lnnoting the resultsreported in'Table 1(b) above for the austenitic stainlesssteel welddepositsof composition according to Table.l(a), itwill be immediatelyseen that the first four specimens reveal many microfissures on thefractured tensile specimen face, as well as numerous breaks in the sideof the specimens. Moreover, it will be seen that all are singularly freeof a second phase. These are the alloys which are free of the ingredientcolumbium. They'are clearly outside of the composition of the alloysaccording to my invention.

The alloys Nos. 839, 813, 805 and 806 of Tables 1(a) and 1(b), whichcontain the required critical amount of the ingredient columbium, fullyanswer to the requirements of the invention. All four specimens are freeof fractured defects on the fractured tensileface. And all fourspecimens contain a certain amount of the required second phase.Although two of the specimens (Nos. 839 and 805), having carbon contentsof 0.060% and 0.066% respectively, with respective columbium contents of3.17% and 1.50%, disclose a single break on the side near the fracture,this evidencing a microfissure or hotcrack at the time of welding, thesingle occurrence is acceptable. The specimens Nos. 813 and 806 withsomewhat higher carbon contents (Nos. 813 with carbon 0.077% andcolumbium 2.08% and No. 806 with carbon 0.100% and columbium 1.10%) aresingularly free of defect. It is in the alloys of the composition ofthese specimens in which a best combination of properties is had.

' The single remaining specimen (No. 816) is not acceptable,

even though a second phase is present; the number of microfissures onthe fractured face is great, and the number of breaks on the side of thetensile specimen is excessive. l attribute the unacceptability of thisalloy to the objectionably low manganese content of 1.31%; in otherregards the com position meets that of the acceptable alloys.

A further series of weld deposits of differing compositions is givenbelow in Table ((1). In these alloys the chromium content ranges fromsome 13% to with nickel from about 1 1% to 21%. For purposes ofcomparison there additionally is included an alloy of the standard AlSIType 310 (chromium about 25%, nickel about 20%, manganese 2% max.,silicon 1.5% max., carbon 0.25% max., and remainder iron).

TAB LE II (a) A study of the results reported in Table ll(b), this withrespect to the compositions reported in Table ll(a), rather clearlyreveals that a composition according to the standard AlSl Type 310 showsmany microfissures on the fractured face of the tensile specimen andmany breaks on the side of the specimen. There is no evidence of thepresence of a second phase. The alloy, of course, is well outside of thecomposition of the alloys of my invention in that there is an absence ofcolumbium and a wholly insufficient amount of manganese. Moreover, thephosphorus content appears to be excessive.

So, also, two further specimens (Nos. 843 and 851) are unacceptable eventhough containing sufficient columbium and sufiicient manganese. Onereveals defects in the fractured face, evidencing microfissures orcracks occurring at the time of welding, and both reveal an excessivenumber of breaks on the side of the specimen. ln both specimens boron ispresent in significant added amount, this being on the order of some0.002% to 0.007%. And in both the nitrogen content is objectionably lowand there is an objectionably high phosphorus content, this latteramounting to 0.029% for the one and 0.021% for the other.

As to the'remaining alloys, all are acceptable, although it is notedthat a best combination of properties, with freedom from microfissureson the fractured face and freedom from breaks on the side of thespecimen is had with the alloys of the higher columbium contents andhigher carbon or carbon plus Chemical composition of nine furtheraustenitic stainless steel weld deposits Specimen N o. 0 Mn 1 S Si Or NiB 1 Cb W N l Boron in wire used for weld filler:

X-N0t added, content generally .001%. YAdded, content may vary fromapprox. .002 to .007%. n Alloys oi the invention. Alloys of theinvention enjoying a best combination of properties. a Ta .85. Mo 1.82.

with examination at 300x. Here again, the properties are re- 55 portedfor weld deposit specimens of 0.505 inch diameter.

TABLE II (b) nitrogen contents (Nos. 833, 844 and 852). Specimen 833,although having a carbon content of 0.047%, has a nitrogen content of0.18%, with a columbium content of 2.28%, which it is felt gives thedesired substantial amount of the second phase, some 5% to 10% byvolume. The alloys of even higher carbon plus nitrogen content (Nos.789, 802 and 803), while acceptable, are not absolutely free of defect.For example, specimen No. 789, which contains tungsten in the amount of3.5% as a substitute for columbium, with carbon 0.041% and nitrogen0.24%, reveals but a small amount of the second phase and two breaks onthe fractured face and a trace of a second phase for the nine welddeposits of Table II (2.)

Appearance of fractured Tensile properties tensile specimens Averagepercent Percent second Percent MF 1 on Breaks 2 on phase in SpecimenU.'1.S Y. elong. Percent fractured side of micro- N 0. K s.1 K s.1 2 RA.face specimen structure 789 a 99 33 46 1 833 N 96 77 26 38 7 844 b 97 7911 11 7 802 82 26 25 1 803 n 04 73 26 34 7 843 87 70 18 10 5 H51. 8'.(i3 '31 30 1 H51. N7 lit) 21') 33 4 'l \'|u-. 3111 8'11 131 .32 Ill 1) 1MI" Mh-rullssnros or lml t'l'lll'iih' which occurred at tho llnw ofwelding show up as /\|lu i of the invention. Alloys of the inventionunjoying n ln'sl. combination of propel-tics.

break on the side of the specimen. Because of a minimum number of breaksthe alloy is acceptable. Specimen No, 802, with columbium 0.48% andtantalum 0.85%, along with carbon 0.110% and' nitrogen 0.28%, whileacceptable, clearlyv falls short of the combination of properties hadwith the best compositions (Nos. 833, 844 and 852). it appears thatwhile tantalum is acceptable as a partial'substitute for columbium, theresults had leave something to be desired; it is with the columbiumaddition that a best combination of properties is realized.

Another series of austenitic weld deposits, these of about 17% to 21%chromium, about 30% to 45% nickel, about 4% to 12% manganese, all ofwhich contain columbium, with or without the further ingredientmolybdenum, and remainder iron, was subjected to mechanical test andexamination. The chemical composition of these alloys, twelve in number,including one of the standard AlSl Type 330, which is free of columbium,is given below in Table lll(a). The tensile properties of the welddeposits of 0.505 inch diameter, as well as the appearance of thefractured tensile specimens and the amount of second phase present inthe microstructure when examined at 300x are given in Table lll(b) whichfollows.

TABLE lll(a) Chemical composition of twelve austenitic weld deposits Areview of the test resultsset out in Table lll(b) above, this withregard to the composition of the specimens as given in Table lll(a),reveals that the alloys of high nickel content and the required chromiumand manganese contents, as well as the required columbium and carboncontents, are characterized by the presence of a second phase and adesired freedom from defects on the fractured face. Such freedom fromdefect evidences a freedom from microfissures or cracks occuringat thetime of welding. A study of the results also reveals in these alloys anacceptable minimum number of breaks on the side oi the specimens. A bestcombination of results. of course, is had in those compositions (Nos.823 and 845) evidencing a complete freedom from face defect and sidebreaks of the fractured specimens.

Although. as indicated, best results are had with compositions free ofbreak. others (Nos. B and 826) are acceptable. These additionallycontain a small amount of boron, this on the order of 0.002% to 0.007%,for the purpose of improving thehot-working characteristics of themetal. While it appears that the boron additionin a measure adverselyaffects the properties to some slight extent, this conclusion must betempered by the further observation that the specimen No. 806

Specimen No. C Mn 1" S Si (Jr Ni B Cl) Mo N B u r 061 12.10 010 008 6017. 83 38. 50 Y 1.13 03 101 4. 42 .010 .013 .78 10. 40 38. 70 X 3. 00.02

. ll 10. 81 008 .010 57 1 .1. 811 30. 54 Y 3. (l4 2. 77 02 050 5. 23 008020 47 20. 24 I 44. 00 X l. 511 2. (i1 03 I Boron in wire used for weldfiller:

X-Not added, content generally .001%. YAdded, content may vary fromapprox. 002% to 007%. Alloys of the invention. Alloys of the inventionenjoying a best combination of properties.

The mechanical properties of the weld deposits of Table. lll(a) arepresented below in Table lll(b). There are reported tionally, thereis'indicated the volume percent of a second phase when examined bymicroscope at 300x. The properties are reported for weld deposits of0.505 inch diameter.

TAB LE III (b) reported in Table 1(a), although not there reported,does, in fact, contain boron in the amount of 0.002% to 0.007% and, asreported in Table 1(b) is free of defect. The acceptable steelsessentially consist of about 17% to about 21% chromium, about 30% toabout 45% nickel, about 5% to about 12% manganese, about 0.05% to about0.20% carbon, with silicon not exceeding about 0.75%, nitrogen at least0.03%, up to 0.007% boron, columbium about 1.5% to 3%, and remaindersubstantially iron, this amounting to at least about 22%.

The further specimen Nos. 812, 827, 829, 831, 834, 835, 849 and Type 330are not acceptable. in specimen No. 812,

Tensile properties, appearance of fracture and percent second phase forthe weld specimens of composition according to Table I11(a)' Appearanceof fractured tensile specimens Average Tensile properties percentPercent second Percent MF 1 on Breaks on phase in Specimen U.T.S., Y.S.,elong. Percent fractured side of microo. K 5.1. K st. 2' RA. facespecimen structure MF=Microfissures or l1ot-cracks which occurred at thetime of welding show up as defects on the face of the fractured tensilespecimen.

2 Breaks on side of tensile specimen are a good measure of weld depositsoundness.

Alloys of the invention. Alloys of the invention enjoying a bestcombination of properties.

the manganese content is unacceptably low, even though, a second phaseis present and but two microfissures appear on the fractured face; theductility is a bit low and corrosion-resistance suffers.

The compositions of the specimen Nos. 827, 829, 831', 834, 835 and 849,as well as the specimen of AlSl Type 330, contain an objectionablenumber of breaks on the side. of each tensile specimen, the specimen No.849 and A181 Type 330 additionally revealing objectionable weld defectsas gauged by the condition of the fractured face. We attribute theshortcomings of the specimen Nos. 827 and 829 to an objectionably lownitrogen content; that of No. 831 to the high phosphorus content of0.020% in combination with high silicon; and of specimen Nos. 834 and835 to the high silicon contents of 1.15% and 0.85%, respectively, thisin combination with boron for the specimen No. 834. The deficiencies ofspecimen No. 849 we attribute to the low manganese content of 4.02%, andto some extent the presence of boron. The inadequacy of the standardAlSl Type 330 is felt to lie in the very low manganese content of 1.72%and the absence of both columbium and tungsten.

We feel that perhaps the necessary importance of the resence of theingredient manganese and that of carbon and columbium, with particularrelation between the same, is best illustrated by presentation of testresults on fusion welds made in grooved bar samples. In every case thecomposition of bar and head is the same, this amounting to about 20%chromium, about 20% nickel, with phosphorus in the amount of about 005%,sulphur in the amount of about 0.010% and silicon in the amount of about0.50%. Weld deposits were examined on a series of welds of the threegroups about 0.75% manganese, about manganese and about manganese, withcolumbium contents of about 0.50%, about 1% and about 2% at eachmanganese level. Samples with carbon contents of about 0.05% and about0.15% were examined for each manganese and columbium figure.- Thecomposition of the various specimens and the degree of cracking reportedfor the weld deposit in each case are given below in Table IV.

TABLE IV phosphorus, sulphur and silicon low, are acceptable. It isnoted, however, that where carbon is on the low side, that is, about0.05%, a best combination of properties is had where the columbiumcontent amounts to about 2% (Heat Nos. 6698-1, 6701-1 and 6702-1 Wherethe carbon is on the high side, however, that is, about 0.15%, the bestcombination of properties is had where columbium amounts to at leastabout 0.50% (Heat Nos; 6696-2 and 6699-2), or about 1% (Heat Nos. 6697-2and 6700-2), or about 2% (Heat Nos. 6698-2, 6701-2 and 6702-2). In allof these alloys the weld deposit is free of cracking, both in the craterarea and in the center area of the weld bead. These results also obtainfor the two highnitrogen grades (Heat Nos. 6702-1 and 6702-2, withnitrogen contents, respectively, 0.14% and 0.24%).

Thus, in conclusion, it will be seen that we provide in our invention aniron-chronium-nickel-manganese alloy and weld which is austenitic andwhich in the as-welded condition is strong, sound and ductile. The alloyin the form of weld wire is particularly suited to the welding of theknown 21-6-9 and 20- -5 chromium-nickel-manganese alloys and others,producing sound, ductile welds of high strength.

Inasmuch as many embodiments may be made of our invention and manymodifications made of the embodiments set out above, it will beunderstood that all matter described herein is to be taken asillustrative and not by way of limitation.

We claim 1. Austenitic alloy essentiallyconsisting of about 12% to about15% chromium, about 18% to about 24% nickel, about 9% to about 13%manganese, about 0.06% to about 0.15% carbon, about 0.03% to about 0.20%nitrogen, about 1.5% to about 3.5% columbium, phosphorus not exceedingabout 0.020%, and remainder substantially iron.

2. Austenitic alloy essentially consisting of about 13% to about 14%chromium, about 18% to about 22% nickel, about 10% to about 11%manganese, about 0.03% to about 0.11% carbon, about 0.06% to about 0.20%nitrogen, about 1.5% to about 3.5% columbium, and about 49% to about 57%iron.

3. Austenitic alloy essentially consisting of about 15% to Degree ofcracking in weld deposit Crater Center of Heat No. 0 Mn Cr Ni Cb N areaead I .78 19. 18 20. 17 .50 05 Very heavy. Moderate. 73 19. 69 20. 12 49.06 Heavy 68 19. 81 19. 93 97 .05 Heavy .64 20.42 20.13 .73 .05 Moderate0. .67 19. 83 20. 06 1. 88 04 Moderate- 0. 70 20.42 20.03 1. 51 .04Light 0. 4. 20.24 19. 88 .53 1 0. 4. 28 20. 12 20. 06 53 4. 86 20.4020.07 1.09 4. 20.41 20. 15 1.06 4. 81 20. 31 20. 09 2. 20 4. 46 20, 1420.27 2. 18 10. 01 20. 03 20. 21 63 9. 92 20. 28 20. 08 62 10. 11 20. 1020.21 1.13 10. 10 20. 13 20.06 1.09 9. 96 20. 14 20. 24 2. 13 10.02 20.17 20.29 2. 16 10. 16 20. 08 20. 17 2. 20 10.25 20. 13 20. 19 2. 24

* Alloys of the invention. I b Alloys of the invention enjoying a bestcombination of properties.

No'rE.-All compositions contain about 005% phosphorus, about 010%sulphur and about .50% silicon.

A review of the results presented above in Table IV quickly reveals thatthe alloys having a manganese content of about 0.75% are in no wayacceptable; cracks ranging from very heavy to moderate are found in allof these specimens (Heat Nos. 6900-1-2, 6901-1-2 and 6902-1-2).

All of the alloys with a manganese content of either about 5% or about10% with carbon contents of about 0.05% or about 0.15% and columbiumcontents of about 0.50%, about 1% or about 2%, along with chromium inthe amount of about 20%, nickel about 20%, nitrogen at least 0.04%, and

amounting to at least about 22%.

5. Austenitic alloy essentially consisting of about 16% to about 21%chromium, about 35% to about 45% nickel, about 9% to about 13%manganese, phosphorus not exceeding about 0.020%, about 0.06% to about0.12% carbon, about 0.06% to about 0.20% nitrogen, about 1% to about 4%columbium, up to about 3% molybdenum and remainder substantially ironthis amounting to at least about 22%.

6. Austenitic alloy essentially consisting of about 22% to about 27%chromium, about 18% to about 23% nickel, about 9% to about 13%manganese, about 0.06% to about 0.10% carbon, about 0.06% to about 0.20%nitrogen, about 1% to about 2% columbium, and remainder substantiallyiron.

7. Austenitic alloy essentially consisting of about 24% to about 26%chromium, about to about 22% nickel, about bon, about 0.03% to about0.30% nitrogen, about 1.5% to about 3% columbium, up to about 2%molybdenum, and remainder substantially iron.

9. Austenitic alloy essentially consisting of about 12% to about 25%chromium, about 12% to about 45% nickel, about 9% to about 13%manganese, about 0.03% to about 0.15% carbon, about 0.03% to about 0.30%nitrogen, about 3% to about 7% tungsten, and about 22% to about 72%iron.

2. Austenitic alloy essentially consisting of about 13% to about 14%chromium, about 18% to about 22% nickel, about 10% to about 11%manganese, about 0.03% to about 0.11% carbon, about 0.06% to about 0.20%nitrogen, about 1.5% to about 3.5% columbium, and about 49% to about 57%iron.
 3. Austenitic alloy essentially consisting of about 15% to about22% chromium, about 10% to about 22% nickel, about 7% to about 13%manganese, about 0.05% to about 0.12% carbon, about 0.03% to about 0.20%nitrogen, about 1.5% to about 2.5% columbium, and remaindersubstantially iron.
 4. Austenitic alloy essentially consisting of about17% to about 21% chromium, about 30% to about 45% nickel, about 5% toabout 12% manganese, silicon not exceeding about 0.75%, about 0.05% toabout 0.20% carbon, about 0.06% to about 0.20% nitrogen, up to 0.007%boron, about 1.5% to about 3% columbium, and remainder substantiallyiron, this amounting to at least about 22%.
 5. Austenitic alloyessentially consisting of about 16% to about 21% chromium, about 35% toabout 45% nickel, about 9% to about 13% manganese, phosphorus notexceeding about 0.020%, about 0.06% to about 0.12% carbon, about 0.06%to about 0.20% nitrogen, about 1% to about 4% columbium, up to about 3%molybdenum and remainder substantially iron, this amounting to at leastabout 22%.
 6. Austenitic alloy essentially consisting of about 22% toabout 27% chromium, about 18% to about 23% nickel, about 9% to about 13%manganese, about 0.06% to about 0.10% carbon, about 0.06% to about 0.20%nitrogen, about 1% to about 2% columbium, and remainder substantiallyiron.
 7. Austenitic alloy essentially consisting of about 24% to about26% chromium, about 20% to about 22% nickel, about 10% to about 12%manganese, about 0.06% to about 0.10% carbon, about 0.06% to about 0.20%nitrogen, about 1% to about 2% columbium, and remainder substantiallyiron.
 8. Austenitic alloy essentially consisting of about 12% to about27% chromium, about 17% to about 24% nickel, about 9% to about 12%manganese, about .03% to about 0.12% carbon, about 0.03% to about 0.30%nitrogen, about 1.5% to about 3% columbium, up to about 2% molybdenum,and remainder substantially iron.
 9. Austenitic alloy essentiallyconsisting of about 12% to about 25% chromium, about 12% to about 45%nickel, about 9% to about 13% manganese, about 0.03% to about 0.15%carbon, about 0.03% to about 0.30% nitrogen, about 3% to about 7%tungsten, and about 22% to about 72% iron.